# Questions tagged [syntax]

Questions on correct (or improved) formulation of Mathematica code to achieve particular results. Use this tag (not "symbol") for questions about all those odd @@ /@ # & and ~ characters.

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### How do I begin to plot an electric field for two point charges?

I'm using Mathematica for the first time and I believe I am having trouble with the syntax. I'm trying to plot a two point electric field and the first step in getting an electric field plot would be ...
1answer
168 views

### How to download Entity data for an interval of dates

I am interested in downloading "TropicalStorm" data for hurricanes with the highest "WindSpeed" occurring in the years 1990 ...
0answers
70 views

### Use of ContainsAny in EntityClass

The documentation page for EntityClass states that Property values in implicitly defined entity classes may make use of Quantity (and intervals of Quantity) for ...
6answers
2k views

### How to efficiently input matrices in Mathematica (compared to what MATLAB offers)

Every time I want to manually input a matrix in Mathematica, it takes me a while since every new row has to be in a separate pair of curly braces. For instance: ...
3answers
182 views

### Writing a conditional expression [closed]

I want to test a specific condition on z1 and z2 such that if z1 is greater than zero and <...
1answer
658 views

### How to extract the first and last element

It is a elemental question maybe,but I am confusing still.If I have a 1-dimension list list a = Range (* {1, 2, 3, 4, 5} *) ...
2answers
96 views

### How to make a address to string

I get a Window address,Of course it should be a string in generally,but I got a non-string by some method,such as paste your clipboard into your notebook directly or other ways.I want to do some ...
2answers
179 views

### Letter g rendered with different descender styles

I've just noticed that Mathematica renders g in two distinct ways: either with a closed descender or a open descender. Seems it happens only for local variables. g ...
1answer
136 views

### What is a proper way to express derivatives with respect to a symbol? [duplicate]

Mathematica's default way of representing derivatives is to express them with respect to a function's input slot. But what if I want to use the chain rule? To replace df(x)/dx with df(0.5 y)/dy 0.5, ...
0answers
57 views

### Why is my array not displayed in TableForm? [duplicate]

Why is the array produced by the following not displayed in TableForm? ...
1answer
74 views

### Why is Carbon and other elements (not available) in StoppingPowerData?

I am trying to look up StoppingPowerData for a number of elements and while this snippet works for several I have tried (Aluminum, Lead, Iron for example), I get a result of (not available), but no ...
0answers
29 views

### How to search effectively for information on MMA Syntax such as “_?” [duplicate]

In another question here, I saw this poincareMetric[u_?VectorQ, v_?VectorQ] := ... Whilst I am familiar with the syntax label_Type, e.g. x_Real, I had not seen ...
1answer
475 views

### How could I define function with function such as Coefficient? [duplicate]

For example, I have eq1=ax+by+cz; and then I want to define new function, $eq2$, as eq2[x_]:=Coefficient[eq1,a]; eq2 ...
2answers
214 views

### How to return the unevaluated variable names from a list of variables which have been declared

I feel like this should have a simple answer but I haven't found anything that works. The toy example of what I want is as follows: ...
1answer
142 views

### Using Case to pull Keys and Values out of a nested Association

The set up: First a helper function: Clear[values] values[m_, l_, v_] := <|"Math" -> m, "Log" -> l, "Value" -> v|> I have a nested Association of ...
2answers
117 views

### How to put the result(and its specified variable) to clipboard

I have a such custom function to do some complicated thing: customFun[str_] := Defer[StringJoin["abc",ToString[#]]&@*StringLength][StringDrop[str,{1,-1,2}]] ...
2answers
109 views

### Roots of an equation output [duplicate]

I'm trying get the critical points of the function $f(x)=(( 1 - 3*(x + 1)^3)/(x^4 + 1))*(x - 2)$ so I took the derivative which is $(16 + 18 x - 9 x^2 - 28 x^3 - 48 x^4 - 18 x^5 + 3 x^6)/(1 + x^4)^2$ ...
3answers
146 views

### Unexpected behavior of MapAt

For the description, I have a simplified problem like the following: MapAt[f[1, #1], {a, b, c, d}, #2] & @@@ {{1, 2}, {3, 4}} will give ...
1answer
121 views

### Can't get the correct answer with this Adaptive Simpson's Rule algorithm

I think the mathematical portion of my algorithm is correct, but I don't really know the mathematica syntax. How do I get the actual function to be evaluated? Code: ...
1answer
80 views

### Why am I getting different answers for expressions containing x^(1/2) and x^(0.5)?

I'm doing a constrained optimization function, where I maximize a function with two arguments subject to a simple constraint: ...
0answers
60 views

### Assigning variables from rules from fit

It became quite clear after running this a few times that my syntax is wrong, but I can't parse out why. Anybody know of a better way to write this? ...
3answers
233 views

### FillingStyle->{None,Automatic} gives unexpected results?

Plot[1 - x^2, {x, -1.5, 1.5}, Filling -> Axis, FillingStyle -> {None, Automatic}] produces an outcomes I find unexpected: In contrast, ...
1answer
45 views

### Learning Shortcut Syntax - Newbie Question [duplicate]

I'm learning Mathematica in order to work with Linear Algebra. I found a good post here about matrix manipulation, but realized that the author used conventions that I couldn't find documented in the ...
2answers
107 views

### Use Accumulate while creating Table

Can I somehow create a list and its cumulative sum at the same time, e.g. with Table: Now I do it in two steps ...
1answer
462 views

### List positions without brackets [duplicate]

Suppose I have a list l which contains the indices of some array a. For instance, l = {{1,1},{1,2}} a = {{a11,a12},{a21,a22}} I want to access the elements of a ...
1answer
513 views

### Using Newton's Method to solve system of equations

I am getting an error that just gets stuck formatting notepad, i don't think there's anything in my code that is wrong, but I'm never sure. ...
0answers
181 views

### Creating 3D image from importing 2D images [closed]

I'm trying to recreate a 3D image from it's 2D slices. I have saved the 2D images as "image1, image2, etc". I've imported them this way: ...
1answer
76 views

### Non-trivial partitions of numbers using Combinatorica

I have made a code which gives back partitions of numbers in two Young diagrams (one Young diagram is trivial). For example, the partitions of 1 are ...
0answers
91 views

### Solve / Reduce runs overnight - should I keep waiting?

I'm pretty new to Mathematica and I'm trying to solve a system of two equations, but both Solve[] and Reduce[] have been running ...
1answer
194 views

### System of nonlinear complex-valued equations using Solve

I'm trying to figure out the proper syntax to use in Mathematica to solve the following system of $6$ nonlinear complex-valued equations in $6$ unknowns $a,b,c,d,e,f$, where $a,d,f \in \mathbb{R}$ and ...
2answers
536 views

### Mathematica can't differentiate when variable name has subscript component

I am not pasting my input code here since the website modifies my code. Instead I am attaching a screenshot of my notebook. Issue: I enter two separate commands (asking Mathematica to differentiate ...
1answer
53 views

### User Defined Functions Not Implementing HoldForm in list of Functions

When I insert the following code in Mathematica, f[x__] := Map[HoldForm, {x}]; g[x_] := x^2; f[g[t], Cos[t], Tan[t]] I get ...
1answer
189 views